Targeting ubiquitin-independent proteasome with small molecule increases susceptibility in pan-KRAS–mutant cancer models
Shihui Shen, Qiansen Zhang, Yuhan Wang, Hui Chen, Shuangming Gong, Yun Liu, Conghao Gai, Hansen Chen, Enhao Zhu, Bo Yang, Lin Liu, Siyuan Cao, Mengting Zhao, Wenjie Ren, Mengjuan Li, Zhuoya Peng, Lu Zhang, Shaoying Zhang, Juwen Shen, Bianhong Zhang, Patrick K.H. Lee, Kun Li, Lei Li, Huaiyu Yang
Shihui Shen, Qiansen Zhang, Yuhan Wang, Hui Chen, Shuangming Gong, Yun Liu, Conghao Gai, Hansen Chen, Enhao Zhu, Bo Yang, Lin Liu, Siyuan Cao, Mengting Zhao, Wenjie Ren, Mengjuan Li, Zhuoya Peng, Lu Zhang, Shaoying Zhang, Juwen Shen, Bianhong Zhang, Patrick K.H. Lee, Kun Li, Lei Li, Huaiyu Yang
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Research Article Oncology

Targeting ubiquitin-independent proteasome with small molecule increases susceptibility in pan-KRAS–mutant cancer models

Abstract

Despite advances in the development of direct KRAS inhibitors, KRAS-mutant cancers continue to exhibit resistance to the currently available therapies. Here, we identified REGγ as a mutant KRAS–associated factor that enhanced REGγ transcription through the KRAS intermediate NRF2, suggesting that the REGγ-proteasome is a potential target for pan-KRAS inhibitor development. We elucidated a mechanism involving the KRAS/NRF2/REGγ regulatory axis, which links activated KRAS to the ATP- and ubiquitin-independent proteasome. We subsequently developed RLY01, a REGγ-proteasome inhibitor that effectively suppressed tumor growth in KRAS-mutant cancer models and lung cancer organoids. Notably, the combination of RLY01 and the KRASG12C inhibitor AMG510 exhibited enhanced antitumor efficacy in KRASG12C cancer cells. Collectively, our data support the hypothesis that KRAS mutations enhance the capacity of the REGγ-proteasome by increasing REGγ expression, highlighting the potential of ubiquitin-independent proteasome inhibition as a therapeutic approach for pan-KRAS–mutant cancers.

Authors

Shihui Shen, Qiansen Zhang, Yuhan Wang, Hui Chen, Shuangming Gong, Yun Liu, Conghao Gai, Hansen Chen, Enhao Zhu, Bo Yang, Lin Liu, Siyuan Cao, Mengting Zhao, Wenjie Ren, Mengjuan Li, Zhuoya Peng, Lu Zhang, Shaoying Zhang, Juwen Shen, Bianhong Zhang, Patrick K.H. Lee, Kun Li, Lei Li, Huaiyu Yang

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Figure 7

The in vivo therapeutic effect of RLY01 in KRAS-mutant tumor suppression.

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The in vivo therapeutic effect of RLY01 in KRAS-mutant tumor suppression...
(A) Top: Response of organoids derived from KRASG12F lung cancer to RLY01. Bottom: Green fluorescence represents calcein AM staining for live cells, while red fluorescence represents propidium iodide staining for dead cells. Representative images from 3 technical replicates with similar results. Scale bars: 500 μm. (B) HCT15 xenograft growth curve (n = 6). Mean weights of tumors on day 21 are shown in the inset. (C) Kaplan-Meier survival curves of HCT15 xenograft model mice (n = 6–7). (D) Colorectal patient xenograft growth curve (n = 7). Mean tumor weight on day 30 is shown in the inset. (E) Representative IHC images of expression of the REGγ targets Lats1 and p21\ Scale bar: 50 μm. (F) Immunoblotting for protein levels of REGγ and REGγ-proteasome substrates with or without RLY01 therapy by peritoneal injection in PDX. Representative blots are shown from 3 independent experiments. (G) Representative images of tumors from LSL-KrasG12D Trp53fl/fl mice. Animals were scanned by micro-CT. Yellow lines indicate areas with lung tumors, and yellow asterisks indicate heart. (H) Box plots showing the tumor volumes at the endpoint of the indicated treatments based on micro-CT (n = 4). The horizontal lines represent the median; the bottom and top of the boxes represent the 25th and 75th percentiles, respectively. The vertical bars represent the range of the data. All data are shown as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001. P values were measured by 1-way ANOVA with Tukey’s multiple-comparison test.